The present invention relates to a paper feeding device for drawing a blank paper from a paper roll and feeding it to a printer or the like.
A paper roll is frequently used as the source of recording paper in a printer and in a facsimile equipment.
Usually, a paper roll is used continuously or used on occasion in response to printing input and other factors with no operator interaction once the roll is set. In many cases no trouble can be found with this arrangement, thereby avoiding maximum inconvenience. However, practical handling of the paper roll is very difficult and the problems such as follows may often occur in the paper feeding process of drawing a length of blank paper from the paper roll.
1) For example, in a process in which a paper roll is freely contactively supported on the bottom of a paper-containing box with no support for the axis thereof and the blank paper is drawn, the paper roll moves up-and-down around the contact point P on the front wall of the housing C as the fulcrum by the drawing force F for the paper roll as shown in FIG. 11 to cause fluctuation of tension F applied on the blank paper and meandering of the blank paper, thus making drawing of the blank paper unstable and often causing disorder in the printed matters.
When the blank paper is drawn by supporting the center O of the paper roll with a fixed shaft R as shown in FIG. 12, it is required to give a damping torque to establish a proper tension F when the paper roll is drawn and thus it is required to provide a mechanism for forming frictional resistance on the fixed shaft R.
As the diameter of the paper roll changes gradually during feeding, a complex mechanism is required to give proper friction, resulting in high equipment cost.
2) A paper roll has a curl, with a part of smaller diameter having a higher curl. In order to prevent trouble, it is required to remove the curl with any method.
To remove the curl from the paper roll, it is required to draw the paper with a tension corresponding the degree of curl in a condition such that the paper roll is curved in a sense opposite to the existing curl. For this purpose, devices in the prior art have been so constituted that a constant brake force is applied on the shaft for supporting the paper roll to draw the paper with a tension not lower than a predetermined level. The effect of the method for removing curl depends on the curve diameter and the tension applied on the paper. The curvation diameter is constant by the diameter of a curl removing roller. Hence, the effect for removing curl is determined by the tension applied on the paper.
The tension applied on the paper should be defined by the brake force of the shaft for supporting the paper roll. The brake force applied on the shaft for supporting the paper roll would be constant in a conventional brake mechanism. There has been a difficulty that the curl could not be removed completely in the course of a gradual reduction in the diameter of the paper roll.
There has been also a difficulty that devices to adjust the brake force of the paper roll in accordance with the varying diameter of the paper roll are too complex and, thus too high in price.
The principal object of the present invention is to provide an economic paper feeding device which can feed unrolled paper in a stable manner.
Another object of the present invention is to provide a simple device which can stably draw unrolled paper from a paper feeding box and feed the unrolled paper to a recording part.
The third object of the invention is to provide a paper feeding device which can feed unrolled paper stably in a condition suitable for use by simple equipment.
The fourth object of the present invention is to provide an economic printer equipment which can handle the blank paper stably and can be used efficiently.